Liquid Ejection Apparatus

Abstract

A liquid ejection apparatus includes a first piezoelectric element, a first pressure chamber, a second piezoelectric element, a second pressure chamber, a nozzle flow path which communicates with the first pressure chamber and the second pressure chamber and which is provided with a nozzle, and a determination unit configured to determine a liquid state at the nozzle based on a first detection signal which represents a change in electromotive force of the first piezoelectric element after at least one of the first piezoelectric element and the second piezoelectric element is driven, and a second detection signal which represents a change in electromotive force of the second piezoelectric element after at least another of the first piezoelectric element and the second piezoelectric element is driven.

What is claimed is: 
     
         1 . A liquid ejection apparatus comprising:
 a first piezoelectric element driven by a drive signal;   a first pressure chamber a volume of which changes in accordance with displacement of the first piezoelectric element;   a second piezoelectric element driven by the drive signal;   a second pressure chamber a volume of which changes in accordance with displacement of the second piezoelectric element;   a nozzle flow path which communicates with the first pressure chamber and the second pressure chamber and which is provided with a nozzle configured to eject a liquid; and   a determination unit configured to determine a liquid state at the nozzle based on a difference between a first detection signal which represents a change in electromotive force of the first piezoelectric element in accordance with a residual vibration generated in the liquid in the first pressure chamber after at least one of the first piezoelectric element and the second piezoelectric element is driven, and a second detection signal which represents a change in electromotive force of the second piezoelectric element in accordance with a residual vibration generated in the liquid in the second pressure chamber after at least another of the first piezoelectric element and the second piezoelectric element is driven.   
     
     
         2 . The liquid ejection apparatus according to  claim 1 , wherein
 a natural vibration period of a flow path from the first pressure chamber to the nozzle is equal to a natural vibration period of a flow path from the second pressure chamber to the nozzle.   
     
     
         3 . The liquid ejection apparatus according to  claim 1 , wherein
 the determination unit includes a difference detector to which the first detection signal and the second detection signal are input, and which is configured to output a signal related to a difference between the first detection signal and the second detection signal, and   a difference determination unit configured to determine the liquid state at the nozzle based on whether a level of the signal related to the difference is within a threshold value.   
     
     
         4 . The liquid ejection apparatus according to  claim 3 , further comprising:
 a drive controller configured to control supply of the drive signal to the first piezoelectric element and the second piezoelectric element, wherein   the drive controller is configured to simultaneously supply the drive signal to the first piezoelectric element and the second piezoelectric element, and   the first detection signal and the second detection signal are simultaneously input to the difference detector.   
     
     
         5 . The liquid ejection apparatus according to  claim 3 , wherein
 the difference detector includes an amplifier circuit configured to amplify an amplitude of at least one of the first detection signal and the second detection signal.   
     
     
         6 . The liquid ejection apparatus according to  claim 3 , wherein
 the difference detector includes a phase delay circuit configured to delay a phase of at least one of the first detection signal and the second detection signal to make the first detection signal and the second detection signal coincide in phase with each other.   
     
     
         7 . The liquid ejection apparatus according to  claim 1 , further comprising:
 a drive controller configured to control supply of the drive signal to the first piezoelectric element and the second piezoelectric element; and   a storage unit configured to store the first detection signal and the second detection signal, wherein   the drive controller supplies the drive signal only to one of the first piezoelectric element and the second piezoelectric element,   the storage unit stores the first detection signal in accordance with a residual vibration generated in the liquid in the first pressure chamber after the drive signal is supplied only to one of the first piezoelectric element and the second piezoelectric element,   the drive controller supplies the drive signal only to another of the first piezoelectric element and the second piezoelectric element,   the storage unit stores the second detection signal in accordance with a residual vibration generated in the liquid in the second pressure chamber after the drive signal is supplied only to the other of the first piezoelectric element and the second piezoelectric element, and   the determination unit determines the liquid state at the nozzle based on the difference between the first detection signal stored in the storage unit and the second detection signal stored in the storage unit.   
     
     
         8 . A liquid ejection apparatus comprising:
 a first driving piezoelectric element driven by a drive signal;   a first pressure chamber a volume of which changes in accordance with displacement of the first driving piezoelectric element;   a first detecting piezoelectric element configured to detect a vibration of a liquid in the first pressure chamber;   a second driving piezoelectric element which is driven by the drive signal;   a second pressure chamber a volume of which changes in accordance with displacement of the second piezoelectric element;   a second detecting piezoelectric element configured to detect a vibration of the liquid in the second pressure chamber;   a nozzle flow path which communicates with the first pressure chamber and the second pressure chamber and which is provided with a nozzle configured to eject the liquid; and   a determination unit configured to determine a liquid state at the nozzle based on a difference between a first detection signal which represents a change in electromotive force of the first detecting piezoelectric element in accordance with a residual vibration generated in the liquid in the first pressure chamber after at least one of the first driving piezoelectric element and the second driving piezoelectric element is driven, and a second detection signal which represents a change in electromotive force of the second detecting piezoelectric element in accordance with a residual vibration generated in the liquid in the second pressure chamber after at least another of the first driving piezoelectric element and the second driving piezoelectric element is driven.   
     
     
         9 . The liquid ejection apparatus according to  claim 8 , wherein
 rigidity of the first detecting piezoelectric element is higher than rigidity of the first driving piezoelectric element, and   rigidity of the second detecting piezoelectric element is higher than rigidity of the second driving piezoelectric element.